2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/212639We derive some new inf-sup and sup-inf formulae for the so-called effective multiplication factor arising in the study of reactor analysis. We treat in a same formalism the transport equation and the energy-dependent diffusion equation.Analysis of PDEsVariational characterizations of the effective multiplication factor of a nuclear reactor coretext